CuI complexes containing the bulky dialkylbiarylphosphane 2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl (tBuXPhos, L) and an ancillary ligand (Cl-, Br-, I-, MeCN, ClO4- or SCN-) have been structurally characterized, namely, chlorido[2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP]copper(I), [CuCl(C29H45P)], 1, bromido[2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP]copper(I), [CuBr(C29H45P)], 2, [2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP]iodidocopper(I), [CuI(C29H45P)], 3, (acetonitrile-κN)[2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP]copper(I) hexafluoridophosphate, [Cu(CH3CN)(C29H45P)]PF6, 4, [2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP](perchlorato-κO)copper(I), [Cu(ClO4)(C29H45P)], 5, and di-μ-thiocyanato-κ2S:N;κ2N:S-bis{[2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP]copper(I)}, [Cu2(NCS)2(C29H45P)2], 6. Iodide complex 3 shows significant CuI-arene interactions, in contrast to its chloride 1 and bromide 2 counterparts, which is attributed to the weaker interaction between the iodide ion and the CuI centre. When replacing iodide with an acetonitrile (in 4) or perchlorate (in 5) ligand, the reduced interaction between the CuI atom and the ancillary ligand results in stronger CuI-arene interactions. No CuI-arene interactions are observed in dimer 6, due to the tricoordinated CuI centre having sufficient electron density from the coordinated ligands.

Lactobacillus spp. are known to accumulate large amounts of inorganic manganese, which protects against oxidative damage by scavenging free radicals. The ability of probiotic L. paracasei ATCC 55544 to maintain viability during long-term ambient storage may be enhanced by this microorganism's ability to accumulate manganese, which may act as a free radical scavenger. To investigate this hypothesis, X-ray fluorescence microscopy (XFM) was employed to determine the changes in the elemental composition of L. paracasei during growth in the MRS medium with or without added manganese. Moreover, manganese uptake by cells as a function of physiological growth state, early log vs. stationary phase was evaluated. The semiquantitative X-ray fluorescence microscopy results revealed that lower levels of manganese accumulation occurred during the early log phase of bacterial growth of L. paracasei cells (0.0064 µg/cm2) compared with the stationary phase cells (0.1355 µg/cm2). L. paracasei cells grown in manganese deficient MRS medium resulted in lower manganese uptake by cells (0.0027 µg/cm2). The L. paracasei cells were further embedded in milk powder matrix using a fluidized-bed drying technique and stored at a water activity (aw) of 0.33 at 25 °C for 15 days. The viability counts of L. paracasei cells grown in MRS medium harvested after 18 h growth and embedded in milk powder matrix retained viability of (9.19 ± 0.12 log CFU/g). No viable L. paracasei cells were observed in the case of embedded L. paracasei cells grown in manganese-deficient MRS medium harvested after 18 h growth or in the case of L. paracasei cells harvested after 4 h when grown in MRS medium. The lower level of manganese accumulation was found to be related to the loss of bacterial viability during storage.

In this paper, we present our findings on a series of copper(ii) 2,2′-bipyridyl (bipy) complexes that inhibit the oxidation of thiosulfate, a current problem in the gold leaching process. The formation of six complexes, five of which have been structurally characterized by X-ray crystallography, illustrate a thermally induced, controllable switching between oxidation states, which in turn inhibits the oxidation of thiosulfate. These findings give further insight and understanding into the rich chemistry of the coinage metals and the hydrolytic processes involved with gold leaching.

Tribenzylphosphane sulfide (SPBn3) reacts with [Cu(CH3CN)(4)]PF6 in a 2:1 ratio to give [Cu(CH3CN) (SPBn3)(2)]PF6 whereas with [Ag(CH3CN)(4)]PF6 in the same ratio it forms [Ag-2(SPBn3)(3)](PF6)(2). The crystal structure of the Cu(I) complex shows it to contain discrete 3-coordinate [Cu(CH3CN)(SPBn3)(2)](+) cations and [PF6](-) anions with the Cu atom lying in the plane formed by the two coordinated sulfur atoms and the nitrogen from the coordinated acetonitrile molecule. The Ag complex is a dinuclear species with the one silver atom being 3-coordinate and the other 4-coordinate. Each of the SPBn3 molecules forms a Ag-C eta(1)-bond with one of the aromatic rings thus blocking the coordination of further SPBn3 ligands. The two Ag centers are linked by a bridging sulfur and a weaker interaction with carbon from the aromatic ring of the same tribenzylphosphane sulfide. (C) 2015 Elsevier Ltd. All rights reserved.

The sterically bulky di(1-adamantyl)benzylphosphane (L) reacts with the copper(I) compounds, CuX (X = CI, Br, I and SCN), in a 1:1 ratio to give the salts CuXL. Single crystal X-ray structures for X = Cl, Br and SCN, show that the complexes exist as dimeric species of the type [Cu2X2L2] with the X groups bridging to give each copper a distorted trigonal-planar coordination geometry with a 'PX2' donor site. When [Cu(CH3CN)(4)]BF4 reacts with L in a 1:2 ratio, the two-coordinated complex [CuL2]BF4 was formed which has a P-Cu-P angle of 169.46(6)degrees, reflecting the influence of the adamantyl groups. The silver(I)1:2 compound, [AgCIL2], has a 'CIP2' donor set with a distorted P-Ag-P bond angle of about 149.02(5)degrees. The reduced coordination numbers, irregular structures and distortions of selected angles are a result of the steric bulk (large cone angle) of L. Some of these structural features may also assist in understanding why Pd(0) complexes of L are effective catalysts for the Sonogashira coupling reactions of arylchlorides and alkynes. (C) 2016 Elsevier Ltd. All rights reserved.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Parallel, tetramolecular G-quadruplex (G4) DNA possessing TINA monomer, (R)-1-O-[4-(1-pyrenylethynyl)phenylmethyl]glycerol, were synthesised and evaluated in complexes with tris(2,2'-bipyridine)ruthenium(II), [Ru(bpy)3 ](2+) , and the Zn(2+) derivative of 5,10,15,20-tetrakis-(1-methyl-4-pyridyl)-21 H,23H-porphine, ZnTMpyP4. UV/Vis, fluorescence, and circular dichroism (CD) spectroscopy showed that the use of G4-DNA as a template resulted in the effective communication between the ligands and the TINA molecule that was covalently attached to the 5'-end and between T and dG at the 5'-end of the dTG4 T sequence. Only one G4-DNA possessing the TINA molecule at the 5'-end of the dTG4 T sequence was able to yield a green-to-blue photochemical upconversion (PUC, λem =420 nm) in the presence of [Ru(bpy)3 ](2+) upon excitation at 500 nm. Different DNA secondary structures can thus be used in DNA-based assemblies for PUC and the way of attachment of chromophores to DNA plays a pivotal role for the creation of a photosynthetic centre.

Six complexes consisting of either 2,6-bis(1H-benzimidazol-2-yl)pyridine (bbp) or 2,2':6',2 ''-terpyridine (tpy) moieties coordinated to ruthenium(II) and attached to (pentaphenoxy)cyclotriphosphazene were synthesised and structurally characterised by single-crystal X-ray diffraction techniques. Two of the complexes are the first examples of structurally characterised mono-protonated Ru(bbp)(tpy) complexes. The new complexes were studied by NMR, electronic absorption and vibration spectroscopy to gain an understanding of their physical characteristics. Remarkably the mono-deprotonated form of the bbp ligand, but only when attached to (pentaphenoxy)cyclotriphosphazene by a pyridyl phosphoester linker, shows an equivalence of the benzimidazole/benzimidazolate moieties on the NMR time scale, but not on the electronic time scale, as evidenced by UV-Vis and resonance Raman spectroscopy. (C) 2015 Elsevier Ltd. All rights reserved.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

In the present study DNA was used as a scaffold for the supramolecular assembly of organic chromophores for photochemical upconversion (PUC). Initially, a green-to-blue PUC was observed using free chromophores in solution: tris(2,2'-bipyridine)ruthenium(II), [Ru(bpy)3](2+), which acts as a long-wavelength absorber (λex = 500 nm), and an in situ energy donor to an acceptor (R)-1-O-[4-(1-pyrenylethynyl)phenylmethyl]glycerol (PEPy or TINA monomer), which acts as an annihilator and short-wavelength photoemitter (λem = 420 nm). Then, DNA duplexes possessing TINA monomers were synthesized, and complexes with [Ru(bpy)3](2+) were investigated. In contrast to the dynamic interactions of [Ru(bpy)3](2+) with TINA monomer free in solution, ground-state complex formation was the predominant mechanism of interaction between [Ru(bpy)3](2+) and DNA duplexes bearing two TINA monomers at the 5' ends as shown by fluorescence, circular dichroism (CD), and UV-vis spectroscopy studies. The use of TINA-modified DNAs led to PUC occurring at concentrations significantly lower than that for free chromophores in solution: 2.5 μM [Ru(bpy)3](2+) and 5.0 μM TINA-modified duplex in the DNA-based systems in aqueous buffer versus 46 μM [Ru(bpy)3](2+) and 4.6 mM TINA monomer for the free donor and acceptor in DCM, respectively. Providing vast capabilities of DNA in the development of novel photonic systems as a result of the controllable organization of various chromophores, this study opens a new perspective for the development of DNA-based light-harvesting systems using PUC.

The synthesis of a series of cyclotriphosphazene and polyphosphazene ruthenium(II) compounds is reported using 2,2′:6′,2″-terpyridine (terpy) and 2,6-di(1H-pyrazol-1-yl)pyridine (bpp) pendant ligands. X-ray crystallography, UV–Vis and resonance Raman spectroscopy have been employed to gain an insight into the physical and coordination behaviour of these complexes and indicate that both the small molecule and their polymeric analogues contain coordinated Ru in an octahedral ‘N6’ environment. The results reveal a difference between the chemistry of the ruthenium(II)-bpp-terpy and ruthenium(II)-bis-terpy complexes and demonstrate a means of grafting functional groups to a polyphosphazene backbone under mild conditions.

Two new polyphosphazene ligands containing 1,10-phenanthrolin-2-olate (L-1) and 2,2 -bipyridine-6-olate moieties (L-2) with 5,5 -di-tert-butylbiphenyl-2,2 -bis(olate) co-substituents were synthesised and then reacted with Fe(Pyridine)(4)(NCS)(2). Variable temperature Mossbauer and electronic absorbance spectroscopies were used to establish the physical behaviour of the new iron-polyphosphazenes. By attaching two bidentate ligands to a geminal phosphorus atom a pseudo tetradentate ligand can be formed that prevents cross-linking when iron is coordinated to the polyphosphazene. (C) 2014 Elsevier B.V. All rights reserved.

Tris(2-cyanoethyl)phosphine (tcep) reacts with the copper(I) compounds, CuX (X = Cl, Br, I and SCN), in a 1:1 ratio to give 1:1 complexes, CuX(tcep), whereas it reacts with CuY (Y = PF6, ClO4, NO3, BH4, CN and CF3COO) in a 2:1 ratio to give the 2:1 complexes, CuY(tcep)(2). Single crystal X-ray structures show that for the anions X = Br and SCN, the complexes are coordination polymers, [CuX(tcep)](n), with the Cu centres being bridged by the anion, and as well, one nitrile arm per tcep ligand coordinates intermolecularly to the Cu to give tetrahedral 'PBr2N' and 'PSN2' coordination spheres respectively. The 2:1 compounds exhibit a variety of structures. For Y = ClO4, CN and CF3COO polymeric structures are formed except for Y = BH4 where the compound is a discrete monomer, [Cu(BH4)(tcep)(2)], with a chelating anion and two monodentate P-bound tcep ligands. Both the compounds obtained with Y = CN and CF3COO also contain coordinated anions and are formulated as [Cu(CN)(tcep)(2)](n) and [Cu(CF3COO)(tcep)(2)](n) respectively. In the case of Y = CN the anion is bridging and the tcep ligands are only P-bound giving a 'P2NC' coordination sphere. In contrast, for Y = CF3COO, the anion is an O-bound monodentate and the tcep ligands bridge to give a 'P2NO' environment for the copper. In the case of Y = ClO4, the anion is not coordinated but a polymeric structure, [Cu(tcep)(2)](n)(ClO4)(n), is formed via bridging tcep ligands linking Cu centres intermolecularly resulting in a 'P2N2' coordination sphere. (C) 2014 Elsevier Ltd. All rights reserved.

The attachment of one and two (R)-1-O-[4-1-(1-pyrenylethynyl)phenylmethyl]glycerol units (TINA, twisted intercalating nucleic acid) at the 5'-end of the 12-mer duplex led to decreased thermal stability at low (50 mM NaCl) salt concentration. This was circumvented by using buffers with high (1.0 M NaCl) salt concentrations, although the duplex with a three-unit 5'-tail (TINA-thymidine-TINA) was less stable than the unmodified DNA. UV-vis and fluorescence spectroscopy studies indicate that the cationic porphyrin ZnTMpyP4 has greater affinity to TINA-modified duplexes than to the unmodified 12-mer duplex at both low and high salt concentrations. An increase in duplex thermal stability (up to Delta T-m + 23 degrees C) was more pronounced upon addition of the porphyrin to duplexes having two TINA monomers at 5'-ends than for unmodified duplex and a duplex with single TINA monomer at each 5'-end. Complex formation resulted in a bathochromic shift observed in the UV-vis spectra for the porphyrin Soret and Q-bands (up to 8 nm) which was also accompanied by changes in their intensities. Energy transfer from TINA to porphyrin showed by fluorescence excitation spectra was accompanied by changes in TINA and porphyrin emission intensities. TINA fluorescence for both monomer and excited dimer was quenched when duplexes were further titrated with the porphyrin, which was attributed to the formation of the ground state complex (major component) and collisional quenching (minor component). Porphyrin fluorescence quenching by K4Fe(CN)(6) showed that TINA-modified duplexes protect porphyrin from quenching slightly better than unmodified duplex but not to the extent of porphyrin protection shown by salmon testes DNA (stDNA). (C) 2014 Elsevier B.V. All rights reserved.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The pyridyloxy-substituted cyclotetraphosphazene ligands, octakis(2-pyridyloxy) cyclotetraphosphazene (L), and octakis(4-methyl-2-pyridyloxy) cyclotetraphosphazene (MeL), react with [Ag(CH3CN)(4)]PF6 and [Ag(CF3SO3)] to form the complexes {[AgL](PF6)center dot 0.5CH(3)CN center dot 0.5C(4)H(10)O}(n) (1), {[Ag2L](PF6)(2)}(n) (2), [Ag2L](CF3SO3)(2) (3), {[Ag2L](CF3SO3)(2)center dot C4H10O}(n) (4), {[Ag-3(MeL)(CH3CN)(2)](PF6)(3)center dot 2CH(3)CN}(n) (5), and [Ag-4(MeL)(CF3SO3)(CH3CN)(3)](CF3SO3)(3) (6), which have been characterized by single crystal X-ray crystallography. The structure of (1) is a coordination polymer containing repeating [AgL](+) units that form 1-D chains. The PF6- anions lie between the sheets formed when the individual chains approach each other such that the pendant pyridyloxy rings have numerous close intermolecular contacts. The triflate solvated salt (4) also is a 1-D coordination polymer, with the individual chains packed close together due to multiple hydrogen bonding contacts between the coordinated triflate fluorine atoms and aromatic hydrogen atoms on adjacent chains, whereas the unsolvated form (3) contains discrete molecules of a dimetallic complex. For the latter two complexes the influence of the solvent on the structures is notable and shows the flexibility of the ligand system. Complex (5) forms a 1-D coordination polymer with the chain being propagated by a silver bound in a near linear manner by a pyridyloxy pendant from one molecule, and by a pyridyloxy from an adjacent molecule. Apart from (4) and (6) all the compounds show this or a similar way of linking the units. Complex (6) forms discrete molecules of a tetra-metallic complex but with one silver involved in an argentophilic interaction at 3.408 angstrom from its symmetry equivalent. This complex is the most metal-rich phosphazene reported for this ligand type, with all eight of the pyridine ligand arms involved in binding the four Ag(I) centres. The formation of silver-ligand bonds, hydrogen bonds, pi-pi stacking, argentophilic and anionic interactions along with subtle kinetic factors influence the self-assembly process.

Mössbauer and electronic absorbance spectroscopy along with variable temperature magnetic moment measurements demonstrate that a cyclotriphosphazene substituted with an iron(II)-bis-2,6-di(1H-pyrazoly-yl)pyridine moiety (1) and its polyphosphazene analogue (2) differ significantly in magnetic behaviour.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The synthesis of the new cyclotriphosphazene (CTP) ligand substituted with a pendant 2,6-bis(benzimidazole-2-yl)pyridine (bbp), namely (pentaphenoxy)[4-{2,6-bis(benzimidazole-2-yl)pyridine-4-yl}phenoxy]cyclotriphosphazene L is reported. The single crystal structure of L shows that the bbp group is attached to the CTP via the oxygen. L reacts with FeX2 (X=ClO4− or BF4-) salts forming the [FeL2]X2 complexes 1 and 2 respectively. For [FeL2](BF4)2 (2), the single crystal structure shows an ‘N6’ coordination sphere around the iron atom. UV–Vis, resonance Raman and Mössbauer spectroscopies and magnetic susceptibility measurements, aided by density functional theory (DFT) calculations, determine the complexes are low spin below 300K but display spin crossover (SCO) behavior above this temperature, hence showing that the addition of a phosphazene to a SCO moiety does not prevent SCO.